Automatic volume control for phonographs



Oct. 8, 1940. Q A HQKANSQN ET AL 2,216,913

AUTOMATIC VOLUME CONTROL FOR PHONOGRAPHS Filed April '1, 1959' 2 sheets- -sheet 1 INVENTORJE 770 A f/oAw/vsom Raw/M0 C James.

7 O. A. HOKANSON ET AL AUTOMATIC VOLUME CONTROL FOR PHONOGRAPHS Oct. 8, 1940.

Filed April 7, 1939 2 Sheets-Sheet 2 Patented Oct. 8, 1940 UNITED STATES PATENT OFFICE AUTOMATIC VOLUME CONTROL FOR PHONOGRAPHS a corporation Application April 7, 1939, Serial No. 266,494

10 Claims.

This invention relates to an automatic control of the sound volume or level of audibility in the reproduction of a phonograph record, and is particularly applicable to selective types of automatic record changing phonographs.

It is the object of the invention to automatically control the volume of sound reproduced by a phonograph record to tone down a normally loud record and increase the volume of sound from a normally quiet record. It is well known that under the same conditions of sound control, different phonographic recordings produce sound at different levels of audibility. The difference may be as great as .03 decibel between the loudest and quietest of a group of recordings taken at random from the run of the phonograph record market. Such a condition is annoying to listenera who must thereby suffer the irritation of regulating the volume with each change of record or of listening to one record which is nearly inaudible while the next record may be deafening in its sound reproduction.

It is, therefore, the purpose of this invention to provide an automatic sound control device which may be preadjusted to approximate equalization of differences in sound emission by the individual records as they are presented for playing. This is accomplished by utilizing the movements of the record changing mechanism functioning in an automatic phonograph, which mechanism moves in relation to the relative location of the record to be reproduced with reference to the other records. changing mechanism is adapted to alter the location of the volume control adjusting means for altering the volume of sound emanating from the electronic devices of the sound circuit actuated by the record while being played.

The invention is applicable to both selective and non-selective automatic record changing phonographs wherever the record to be produced or the record changing mechanism assumes a different relative position from that of any other such record or mechanism.

As illustrative of one application of the invention it is herein shown as applied to an automatic record changer of the selective type such as that disclosed in Letters Patent No. 2,096,718, issued October 26, 1927, on an application filed by Otto A. Hokanson, and more particularly to a similar phonograph disclosed in his application Serial No. 169,442, filed October 16, 1937.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims;

Such movement of the record Fig. 1 is a side elevation showing a part of a selective record changing mechanism to which the automatic volume control is attached. Fig. 2 is a perspective view of the cams and mechanism for actuating the volume control. Fig. 3 is a sec- 5 tion taken on the line 3-3 of Fig. 2. Fig. 4 is a side elevation of the volume control. Fig. 5 is a section taken on the line 55 of Fig. 4. Fig. 6 is a side elevation of the volume control, showing the opposite side from that shown in Fig. 4. Fig.

'7 is a perspective View illustrating a modified form of the control member. Fig. 8 is an enlarged section taken on the line 88 of Fig. 7.

In the drawings, for purpose of illustrating one application of the invention, there is shown a 15 portion of an automatic selective phonograph of the character more fully described in the abovementioned patent and application, wherein there is provided a turntable l carrying a series of records 2 to be reproduced, which records are divided 20 into a lower group supported by the turntable, and an upper group supported by the fingers. In the operation of this machine all the records are normally supported upon the turntable in a stack with the fingers 3 disengaged therefrom. The 25 record is selected by raising or lowering the turntable to bring thedesired record to a predetermined elevation. Thereupon the fingers. are brought into contact with the under surface of the record immediately above the record to be re- 30 produced. Said fingers are then elevated to raise all of the superimposed records upwardly in spaced relation and permit free movement of the reproducer 4 over the record thereby exposed. The turntable is raised to the record selecting 35 position by an arm 5 having a bifurcated hooked end engaging under a pin 6 on the turntable support, the elevation of the arm 5 being effected and controlled by the cam l.

The opposite end of the arm 5 from the bifur- 40 cated end is provided with a pair of jaws 8 and is pivoted adjacent thereto upon a standard 9. Extending at right angles to said arm and pivoted upon the adjacent face of the standard 9 there is a short lever I!) having a head ll projecting with thejaws 8 of the lever 5. Said lever I0 is provided at its opposite end with similar jaws l2 which engage with the head of a lever l3. Said lever l3 is pivoted to the standard 9 adjacent its engagement with the lever [0. Thus, the movement of the arm 5 responding to the position of a predetermined record transmits a corresponding movement to the extended end of the lever K! through the lever Ill.

The end 14 of the lever 13 projects through an aperture l5 formed in a sleeve l6 slidably mounted on a post I1, and through a slot 19 formed vertically in said post so as to permit vertical movement of the lever 13 and sleeve l6 thereon. Formed integral with the sleeve l6, which provides a vertically movable guide member, and as a continuation thereof, there is a laterally-extending cam flange 22 adapted to move up and down in a vertical plane with the lever l3 to a position determined by the particular record to be reproduced.

Arranged in relative vertical position corresponding with the number of records to be reproduced, there is a plurality of threaded holes provided in the cam flange 22 which are shown herein in their numbered relation. Mounted in each of said holes there is a volume control actuating cam having a threaded cylindrical body 25, such as a screw, provided at one end with a radially extending head 26 in the form of a segment of a sphere whose altitude is in prolongation of the axis of said body. Said body or screw is provided on its opposite end with a suitable slot for the reception of an adjusting tool, such as a screw driver blade, and is provided with a lock nut 21 adapted to bear against the face of the cam flange for securing it in adjusted position.

In Figs. 7 and 8 there is shown a modified form of cam flange 24 similarly slidable on a standard in the manner above described in respect to cam flange 22. In this modified form, said flange is provided with a number of suitably arranged apertures, preferably of rectangular outline, corresponding in number and relative arrangement with the records to be reproduced. In each aperture there is slidably fitted a volume control actuating cam 28 preferably of substantially rectangular cross section. The actuating end 29 of each cam is formed to pro vide a suitable cam-like actuating surface as may be most suitable for the purpose. Said cams are adjustable in directions at right angles to the plane of movement of the flange 24 and may be locked in their adjusted position by means of screws 30 having conical points 3l which mate with the grooves 32 cut in the shank of each cam. On the projecting portion of the shank of each of said cams there is a series of indicating marks 33 arranged to be visible for indicating the position of adjustment, or the particular groove engaged. Each of the locking screws 30 is provided on its exposed end with a tool receiving groove 34, and may be identified by number with a corresponding record to be reproduced, as above described with respect to the cam flange 22.

Supported adjacent the cam flange there is a bracket 35 which is pierced to receive sleeve 36 of volume control 31, which sleeve is retained by a lock nut 38. Said volume control 31 is provided with an arcuate cam follower 39 on an actuating lever arm 40. Said arm 40 is secured about an arcuate portion of the control so as to extend upwardly therefrom into position for engagement by one of the several actuating cams 25 or 28. Formed on the opposite end of the arm from the follower 39 and projecting downwardly from the volume control there is a perforated lug 4| having connected thereto a spring 42 which in turn has its other end connected with an anchor member 43.

The volume control is connected in the usual manner in the electric sound circuit, as shown herein, there being three connections, one to the ground, one to the amplifier and one to the pickup of the phonograph. The spring 42 maintains the cam follower 39 in engagement with one or the other of the actuating cams 25. Depending upon the adjustment given to the respective cams 25, the volume control is oscillated thereby about its pivotal mounting to vary the volume of sound produced by the particular record associated with the particular actuating cam engaged.

In operation, when new records are placed upon the phonograph they are each tested as to the volume of sound produced thereby. Each of the actuating cams is thereupon adjusted by engaging a tool in the adjusting grooves formed in their ends, as shown in Figs. 7 and 8. The actuating cams 28 of modified form are adjusted by a sliding action and locked in adjusted position by the screws 30. If a particular record is too loud, the actuating cams are retracted, which permits the spring 42 to oscillate the volume control in a counterclockwise direction so as to offer more resistance in the electric sound circuit. On the other hand, if the sound produced by a particular record is not sufliciently audible for the purpose desired, its associated actuating cam is moved outwardly so that the volume control is oscillated in a clockwise direction against the tension of spring 42.

After the individual actuating cams are adjusted so that the desired volume or sound is produced from each record in the machine, the selection and playing of such records results in the desired volume of sound in accordance with the pre-adjustment. Thus, in the particular application here described, as each individual record is placed in reproducing position the level of the turntable will be varied accordingly so that a corresponding position of the cam flange 22 will be established through the arm 5 and lines l0 and I3. This particular position of the turntable, arm 5, levers and flange 22 will bring the corresponding actuating cam 25 into actuating engagement with the cam follower 33.

For purposes of illustration a suitable volume control or rheostat is illustrated in Figs. 4, 5 and 6. This control is of the well known type with certain variations in its structure to more suitably adapt it to the purpose herein described. Within sle ve 36 a shaft 46 is rotatably held by an expanded flange 41, flange 48 and friction washer 49. Shaft 46 is provided with a shoulder which locates a disk 51 of insulating material, such as laminated Bakelite held in place by a metal ring 52 pressed on the smaller diameter of shaft 48. On each of its faces disk 5! bears contact rings 53 suitably attached, as by eyelets, each of which rings 53 has a segmental section biased away from the faces of disk SI, and having at its miclpeint a foot 55 extending substantially at right angles thereto. Each foot 55 forms a tractor for a contact ring 56 into the central opening of which it protrudes, serving to move said ring in a circular path in connection with shaft and disk 5| when said shaft and disk are revolved.

A pair of rings 59 stamped from an insulating material, such as vulcanized fiber, is suspended concentric to and surrounding shaft 45 by conductors 51. Said conductors 5'! are integral with arcuate contact rings 53 and terminals E0, being attached to end discs 62 by suitable means such as eyelets 6| Conductors 5'! also serve as springs, being biased toward one another, thereby holding arcuate contact rings 58 in contact with rings 53 on disk 5|. Rings 59 serve as stiffeners for the arcuate rings 58 and extend inwardly beyond the inner borders of said rings to prevent their con tact with shaft 46 in the event, ofshock or vibration.

The end disks 62 are stamped from. strong insulating material, such as laminated Bakelite, and are pierced centrally with intruding wedges 63 which prevent rotational movement between disks 62 and bushings 64 that are pressed into the cen tral orifices. One disk rotates upon sleeve 36, being retained thereon between flange 55 and collar 66, the latter being retained by striking or upsetting the inner end of sleeve 36. The other end disk 62 revolves upon shaft 465 at the free end of its smaller diameter. End disks 62 bear upon shaft 46 at the free end of its smaller diam eter. End disks 62 bear upon their inward faced segments of carbonized paper 6? whose boundaries are indicated by broken lines in Figs. and 6. Said disks 62 are suitably pierced for rivets l2 and one is also notched at each quadrant for the reception. of cusps 68 and connectors ti, ll. Said segments ii! are secured to end disks 62 by rivets 12 which put said segments into electrical contact with connectors H.

A cylinder of sheet insulating material "H3 holdsend disks 62 in spaced relationship such that arcuate rings 58 are held in electrical conducting contact with rings 53,. and rings 56 are pressed firmly against the inward faces of the segments of carbonized paper tl.

A cup or shell 73 of sheet metal contains mechanism described above, it being cut away as at M to avoid contact with electrical conducting parts Gil, 68, ll, '52 thereby constituting the body of the volume control 37. Upon its edge it bears four equally spaced protruding cusps 63 which fit into the aforesaid notches at each quadrant of one end disk, against the face of which disk they are bent and act as retaining hooks.

The arm 48 of cam follower 35.1 is fastened as by soldering, welding or riveting to the outer surface of one quadrant of cup 13, and extends a suitable distance tangentially thereto in a direction parallel with the connector (iii.

A slot 15 is cut transversely of the end of shaft 4E within sleeve 36 for the reception of a key by which said shaft may be rotated for adjustment. A stop and car, not shown, respective- 1y located on disks 5! and 62 limit their rotation to prevent rings 56 from traveling beyond the ends of segments 51.

The volume control, such as has just been described, is embodied in the electric sound reproduction circuit in the usual manner as now commonly employed and understood, wherefore no detailed description thereof will be necessary herein. A slight oscillatory movement of the volume control in either direction, effected through the interaction of the adjusted actuating cams and spring 42, effect the desired variation in the volume of sound resulting from the reproduction of the particular record associated with the particular actuating cam.

Wherein the invention has herein been il1ustrated as applied to that type of selective phonograph wherein the record to be reproduced depends upon the elevation of the turntable, the invention is equally applicable to any other type of record changer wherein the record changing mechanism may be connected with the actuating cams in such manner as to position them for actuating the cam follower depending upon the particular record presented for reproduction.

The invention claimed is:

1. In a phonograph wherein a series of records are selectively placed in reproducing position,

and oscillate said device to said variable positions between limits, and means for operatively connecting said cam members to said mechanism to present a designated member to said device for engaging and oscillating it to one of said positions corresponding with the record to be reproduced.

2. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a volume control device in said circuit, means for supporting said device for oscillation to variable positions between limits efiecting the volume of sound, a spring for urging said device in one direction, a projecting arm thereon, a series of cam members adapted to be brought into engagement with said arm for urging said device in the opposite direction, means for adjusting each of said cams to a variable position between limits, and means actuated by said mechanism for moving one of said members into operative engagement with said arm depending upon the record to be reproduced.

3. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a volume control device in said circuit, means for supporting said device for oscillation to vary the volume of sound, a slidable support mount-ed adjacent thereto, a series of cam members on said support each corresponding to a record to be reproduced, means for adjusting the relative positions of said cam members, and an operative connection between said support and said mechanism for causing the member corresponding to the record to be reproduced by said mechanism to engage and operate said volume control device for causing a predetermined volume of sound to be reproduced.

4. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a volume control device in said circuit, means for rotatably supporting said device to vary the volume of sound, a cam follower extending upwardly from said device, a cam plate vertically slidable adjacent said device having a plurality of adjustable cam members thereon adapted to be brought into individual engagement with said cam follower, and a series of 'levers interconnecting said mechanism with said cam plate for presenting to said cam follower the cam member corresponding to the record tobe reproduced by said mechanism, whereby a predetermined volume of sound will be effected by the actuated position of said volume control device.

5. In a phonograph having a plurality of records for automatic placement in reproducing position, the combination with the record changing and reproducing mechanism, of an electric sound circuit therefor, a sound volume control device in said circuit, manually actuated rotatable means for setting the resistance in said control device to establish a normal volume of sound produced by said reproducing mechanism, additional means operable to vary the resistance in said device from that manually set, and means interconnecting said record changing mechanism and additional means for automatically maintaining a predetermined volume of sound for each record reproduced.

6. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a single sound volume control device in said circuit, means for manually adjusting said device to establish the desired volume of sound, and additional means on said device actuated by the record selecting mechanism to independently and variably establish the level of audibility in the reproduction of each individual record.

'7. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a single sound volume control device in said circuit, means for manually adjusting said device to establish the desired volume of sound, a control member on said device movable to alter the sound volume, and a plurality of manually adjustable members operatively connected with said record selecting mechanism for actuating said control member whereby the level of audibility of each record may be predetermined.

8. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a single sound volume control device in said circuit, means for manually adjusting said device to establish the desired volume of sound, a control member on said device movable to alter the sound volume, a series of manually adjustable members engageable with said control member, and mechanism for operably connecting said members with said record selecting mechanism correlated with each of said records respectively, whereby the reproduction of a record selected by said mechanism will cause its correlated member to actuate the control member for establishing a selected level of audibility therefor.

9. In a phonograph wherein a series of records are selectively placed in reproducing position, the combination with the record selecting and reproducing mechanism, of an electric sound circuit, a volume control variable resistance unit in said circuit, a series of cam members, means for adjusting said members to variable positions, means for operably connecting said cam members to said mechanism to present a designated member to said resistance unit, and means actuable by said cam members respectively for varying the resistance of said unit upon being presented thereto for establishing a predetermined volume of sound for each of said records by the corresponding record selected by said mechanism.

10. In a phonograph having a plurality of records for automatic placement in reproducing position, the combination with the record changing and reproducing mechanism, of an electric sound circuit therefor, a single sound volume control device in said circuit, means for manually adjusting said control device to establish a normal volume of sound produced by said reproducing mechanism, and means interconnecting said record changing mechanism and said volume control operable to automatically adjust it to establish a volume of sound above or below the established normal volume of sound for each record placed in reproducing position.

OTTO A. HOKANSON. RICHARD C. JONES. 

